To obtain a better understanding of the structure and functions of the avian retravirus RNA-directed DNA polymerase, studies were continued comparing the properties of the single subunit DNA polymerase (alpha) and the major two subunit enzyme (alpha beta) of avian myeloblastosis virus (AMV). The tightly bound subunits of AMV alpha beta DNA polymerase were dissociated by exposing the enzyme to either dimethyl sulfoxide or 1,4-dioxane followed by separation of the subunits by phosphocellulose chromatography. The enzymatically active alpha subunit was purified to homogeniety while beta always had small quantities of alpha present. Poly(U)-sepharose purified or dioxane purified alpha DNA polymerase was not able to bind, under numerous experimental conditions, to purified tRNATrp as analyzed by Sephadex G-75 chromatography while alpha beta bound tightly to this primer. These results suggested that the beta subunit is necessary for in vitro recognition of tRNATrp. Other results suggested that virion associated tRNATrp exists in two conformational isomers. With 10 mM MgCl2 present, alpha beta DNA polymerase bound maximally 45% of the 32P-tRNATrp species while with no MgC12 present, 90% of the tRNA was bound by the enzyme. Further analysis is necessary to verify that virion associated tRNATrp, like E. coli tRNATrp, exists in two conformational isomers. BIBLIOGRAPHIC REFERENCES: D.P. Grandgenett. 1976. Dissociation of alpha beta DNA polymerase of avian myeloblastosis virus by dimethyl sulfoxide. J. Virol. 17, 950-961. D.P. Grandgenett, A.J. Faras, and A.C. Vora. 1976. Different states of avian myeloblastosis virus DNA polymerase and their binding capacity to primer tRNATrp. Virology 75, 26-32.